A new drug is showing promising results for breast cancer patients, potentially creating a new treatment option for thousands of individuals.

The drug, ENHERTU, targets a protein responsible for breast cancer growth and has been shown to work against tumors with very low levels of the protein HER2, according to new research.

“This antibody-drug combination takes the chemotherapy directly to the HER2-positive breast cancer cell,” said Sandhya Dhanjal, MD, an oncologist at St. Vincent’s Medical Center in Bridgeport. “This is a more targeted option. It’s a very exciting development.”

It will not cure the cancer but it will help to control cancer in patients who have already received treatment, at least one or two rounds of chemotherapy. Patients in the study had advanced stage 4 breast cancer and the drug lengthened the amount of time that the cancer did not progress. It also significantly improved survival rates compared to patients who received standard chemotherapy. ENHERTU is being offered to patients who qualify at St. Vincent’s Medical Center.

Oncologists have typically categorized breast cancers as either HER2-positive, meaning the cancer cells have more of the protein than is typical, or HER2-negative. With this advancement, “HER2-low” will be a new category which will account for roughly 60 percent of breast cancer patients.

“Many patients will be reclassified as HER-2 low so that this drug will be an option for them,” Dr. Dhanjal said. “There has not been a targeted treatment for this group of patients with HER2-low breast cancer in the past.”

Dr. Dhanjal said this advancement is representative of the future of cancer treatment, using more targeted therapies.

“We are finding a lot of new markers of cancer that we are targeting,” she said. “By collecting data on different mutations that are creating cancer cells, we can develop drugs that target those cancers more effectively.”